Tiger Swallowtail

fws.gov

Description: The Tiger Swallowtail Butterfly is one of about 550 species of Swallowtail butterflies. The name “swallowtail” comes from the two small posterior extensions that resemble the tail of a swallow (bird with forked tail). The swallow-like tail is thought to trick predators into thinking the tail end is actually the head. It is very common to observe these butterflies with a missing portion of the swallow-like tail, undoubtedly serving its purpose in protecting the butterfly.

The Swallowtail is one of our largest butterflies. Its wingspan can extend as far as 16 centimeters (about 6 inches). The male is pale yellow with four black “tiger” stripes on each wing. Some may have blue spots on the hind wings. In much of its range, female Tiger Swallowtails look completely different from males and are entirely black with blue and orange spots toward the tail region.

Range: The Eastern Tiger Swallowtail Butterfly ranges from southern New England throughout the east and Midwestern United States to the western Great Plains. The similar Western Swallowtail Butterfly is found in the western United States.

Life Cycle: The female lays round green eggs on the leaves of its host plants. When the eggs hatch, the larva immediately begins eating and will readily eat leaves from a variety of different plants, especially wild cherry leaves, willow, and cottonwood. The larva are said to resemble bird droppings. As the larva grow into caterpillars, they turn bright green and have a large set of false eyes toward the end of the thorax. The false eyes are black with yellow outlines. As the caterpillar grows, it molts (sheds exoskeleton) several times. When the caterpillar is ready for its metamorphosis, it spins a silk mat on a leaf (which causes a curl in the leaf) and forms its chrysalis. In about three weeks, the butterfly emerges.